Use self and the slow python expression
Expressions containing:

variable names: only ASCII characters.
literals: floating point and decimal integer.
globals: frame
constants: pi, True, False
operators: +, -, *, /, ==, !=, &lt;, &lt;=, &gt;, &gt;=, and, or, not,
conditional operator A if B else C
standard functions: min(), max(), radians(), degrees(), abs(), fabs(), floor(), ceil(), trunc(), round(), int(), sin(), cos(), tan(), asin(), acos(), atan(), atan2(), exp(), log(), sqrt(), pow(), fmod()
blender provided functions: lerp(), clamp(), smoothstep()

fall into Simple expression category and:

are evaluated directly, which improves performance on multi-core systems
are evaluated even when Python script execution is disabled
don't get the &quot;Slow Python expression&quot; flag